Table1.
Characteristics by Quartile of Percent of Sleep Time Spent in REM
| Quartile | |||||
|---|---|---|---|---|---|
| Q1: <14.8 | Q2: 14.8 to <19.6 | Q3: 19.6 to <23.7 | Q4: >=23.7 | ||
| Variable | (N= 690) | (N= 684) | (N= 698) | (N= 701) | P-value |
| Age, years, mean ± SD | 77.5 ± 5.7 | 76.5 ± 5.6 | 75.8 ± 5.5 | 75.6 ± 5.2 | <.001 |
| Body mass index, kg/m2, mean ± SD | 27.3 ± 4.1 | 27.1 ± 3.9 | 27.0 ± 3.6 | 27.2 ± 3.6 | .68 |
| Race/Ethnicity, % | |||||
| Caucasian | 91.9 | 91.8 | 90.8 | 88.5 | .24 |
| African American | 3.0 | 2.3 | 3.2 | 4.4 | |
| Other | 5.1 | 5.9 | 6.0 | 7.1 | |
| One or more IADL impairments, % | 25.7 | 21.5 | 17.5 | 17.6 | <.001 |
| History of medical conditions, % | |||||
| Hypertension | 55.9 | 48.5 | 48.4 | 47.5 | <.01 |
| Stroke or transient ischemic attack | 13.9 | 12.4 | 8.9 | 9.0 | <.01 |
| Diabetes | 14.8 | 12.4 | 12.9 | 12.4 | .51 |
| Parkinson’s disease | 1.7 | 0.9 | 0.6 | 0.7 | .12 |
| COPD | 7.0 | 5.9 | 3.3 | 4.9 | .02 |
| Coronary heart disease* | 38.0 | 32.7 | 29.1 | 30.0 | <.01 |
| Number of medical conditions, %† | |||||
| 0 | 23.8 | 29.9 | 33.8 | 35.1 | <.001 |
| 1–2 | 63.6 | 59.7 | 59.5 | 56.4 | |
| 3+ | 12.6 | 0.4 | 6.8 | 8.4 | |
| Current antidepressant use, % | 11.6 | 6.3 | 6.7 | 5.1 | <.001 |
| Current benzodiazepine use, % | 5.4 | 4.8 | 2.7 | 4.4 | .09 |
| Current sleep medication use, % | 2.0 | 1.3 | 3.0 | 1.7 | .14 |
| Geriatric Depression Scale score (range 0 to 15), mean ± SD | 2.1 ± 2.4 | 1.7 ± 2.1 | 1.5 ± 1.9 | 1.6 ± 2.0 | <.001 |
| Education, % | |||||
| < high school | 7.4 | 5.1 | 3.6 | 4.0 | <.01 |
| high school | 17.5 | 17.1 | 14.8 | 15.6 | |
| >high school | 75.1 | 77.8 | 81.7 | 80.5 | |
| Alcohol intake, drinks/week, % | |||||
| 0–2 | 64.2 | 57.8 | 57.2 | 59.3 | .09 |
| 3–13 | 32.0 | 36.1 | 36.8 | 35.6 | |
| 14+ | 3.8 | 6.2 | 6.0 | 5.2 | |
| Smoking, % | |||||
| Never | 40.4 | 37.6 | 42.1 | 38.9 | .44 |
| Past | 57.1 | 61.0 | 55.9 | 59.3 | |
| Current | 2.5 | 1.5 | 2.0 | 1.7 | |
| Caffeine use, mg/day, mean ± SD | 225.3 ± 239.4 | 235.7 ± 232.2 | 232.7 ± 247.4 | 250.2 ± 268.2 | .51 |
| Physical Activity Scale for the Elderly (PASE) score, mean ± SD | 136.6 ± 73.4 | 148.4 ± 71.3 | 148.0 ± 69.8 | 151.8 ± 69.4 | <.001 |
| Self-rated health good/excellent, % | 83.0 | 87.3 | 90.7 | 88.0 | <.001 |
P-values for continuous data are from an ANOVA for normally distributed data, Kruskal-Wallis test for skewed data.
P-values for categorical data are from a chi-square test for homogeneity.
*
Coronary heart disease includes myocardial infarction, angina, congestive heart failure, bypass surgery, angioplasty, or heart valve replacement.
†
Medical conditions include stoke/transient ischemic attack, coronary heart disease, diabetes mellitus, chronic obstructive pulmonary disease, Parkinson's disease, and hypertension.
SD=standard deviation; REM=rapid eye movement; IADL=instrumental activities of daily living; COPD=chronic obstructive pulmonary disease.